Specifically, the Cucurbitaceae (gourd family) include some food species, such as squash, pumpkin (both from Cucurbita), watermelon (Citrullus vulgaris), and cucumber and melons (Cucumis).

[3][4] Members of the Cucurbitales form an important component of low to montane tropical forest with greater representation in terms of the number of species.

[3] Compared to other flowering plant orders, the taxonomy is poorly understood due to their great diversity, difficulty in identification, and limited study.

In contrast, there is convergent evolution with other groups not related due to ecological or physical drivers toward a similar solution, including analogous structures.

[5] Some of the synapomorphies of the order are: leaves in spiral with secondary veins palmated, calyx or perianth valvate, and the elevated stomatal calyx/perianth bearing separate styles.

Early molecular studies revealed several surprises, such as the nonmonophyly of the traditional Datiscaceae, including Tetrameles and Octomeles, but the exact relationships among the families remain unclear.

[3] The lack of knowledge about the order in general is due to many species being found in countries with limited economic means or unstable political environments, factors unsuitable for plant collection and detailed study.

Modern molecular phylogenetics suggest the following relationships:[2][3][8][9][10][11][12][13] Fagales (outgroup) Apodanthaceae Anisophylleaceae Corynocarpaceae Coriariaceae Cucurbitaceae Tetramelaceae Datiscaceae Begoniaceae